Remember, Windows 8 is for tablets too... so the ribbon makes sense for the venerable sausage-fest that'll be playing around with the screen... double tapping... touch interface...
Too crude?
I'm kind of glad about some of the changes, but without actually using it, I can't pass judgment. There are lots of little things that got changed with Explorer going from XP to Vista to 7, most of the changes were not positive. Like the removal of the status bar showing you the current directory size... i mean, really? How about expanding a folder in the tree view only to have the folder scroll to the bottom of the list, forcing you to scroll down just to look at the contained folders (in the tree view). Then there was the removal of the 'up' button too, which i did actually find useful.
At least it looks like the status bar is making a comeback, instead of that completely useless 'details' bar - that bar was huge and spent more time showing you nothing than anything useful, complete waste of space. Other notable details includes the comeback of some of the 'power tools' released under XP, like 'open command prompt here...'. Basically, it looks like windows XP file manager with library functions and a ribbon interface.
Speaking of libraries; if they don't add network support - complete fail. The removal of the favorites menu was silly too, save a bookmark to a common folder, that was great in XP. But no, Vista and 7 wanted people to use libraries, great, but if the directory is on a network, it's a no go. Yes, I pay too much attention to the little things...
Worth mentioning though that it should be possible to disable the ribbon, since the GUI is very customizable. Microsoft should at least give the option to allow users access to a standard menu with context support and ditch the ribbon entirely. You can enable the standard menu under 7, so it shouldn't be a stretch for 8... but we know how MS can be.